The present invention relates to a device for inflating an air cushion, air bag, or the like.
Inflatable bag restraint systems have been shown to reduce the seriousness of injuries and number of fatalities resulting in motor vehicle accidents. There exists a number of means for inflating an air cushion or air bag such as utilizing a quantity of stored gas which is selectively released to expand the air bag. Alternatively, a gas source derived from a gas generating material propellant such as sodium azide, which upon ignition thereof generates a sufficient quantity of gas to expand the air bag. The third type of gas source results from a combination of the stored compressed gas and a gas generating or enhancing material. This last device is often referred to as an augmented gas or hybrid inflator. Various hybrid inflators have been shown in the past such as those illustrated in U.S. Pat. Nos. 3,756,621 and 3,895,821. The inflator shown in U.S. Pat. No. 3,756,621 uses a separate squib or initiator to ignite the propellant and an actuator to open an exit passage to initiate compressed gas flow. U.S. Pat. No. 3,895,821 mounted a single squib outside the pressurized environment of the pressure vessel to ignite the propellant. In that invention a single squib and propellant chamber or housing is placed in a compressed inert gas environment. Upon initiation of the propellant, a heated media is generated, comprising hot gas and particulates which are directed by a discharge nozzle into a small mixing cavity or chamber adjacent a rupturable disk causing same to burst, initiating gas flow into an air bag. Hot gases continue to be emitted from the propellant chamber and mix with the cold pressurized gas in a small mixing chamber before continuing into the bag to inflate same. The present invention yields advantages in relation to the prior art in that the number of leak passages are reduced, electrical leads are shielded from the harsh environment of the inflation gases, and the inflation rate is controlled.
It is an object of the present invention to provide a hybrid inflator which can rapidly and efficiently generate a sufficient quantity of gas to inflate a cushion or air bag during a vehicle crash situation. A further object of the present invention is to provide an inflator for an air cushion or air bag which improves upon the deficiencies of the prior art.
Accordingly the invention comprises: a hybrid inflator for an cushion comprising in one embodiment a hollow, cylindrical sleeve enclosed at both ends by pyrotechnic actuator assemblies. The enclosed sleeve comprises a pressure vessel for the storage of a quantity of pressurized inert gas such as Argon. A trace amount of helium may be present to facilitate leak testing of the pressure vessel. The first actuator assembly comprises an actuator, detonator or squib for generating a shock wave to break a frangible disk member to enable gas flow through flow orifices associated with the first actuator assembly. A second actuator assembly is positioned opposite from the first actuator assembly and includes another detonator, initiator, squib or the like for initiating the burning of a quantity of propellant. The propellant elevates the temperature of the stored inert gas to increase its volume prior to inflating the air cushion. In one embodiment of the invention a second frangible disk, forming part of the pressure vessel, is positioned opposite the propellant and upon being broken permits heat generated by the propellant to enter the pressure vessel. In another embodiment of the invention, upon breaking the second disk a second flow path is created to permit the egress of the heated inflation gas out from the pressure vessel. In an embodiment of the invention, only a single actuator assembly is used which upon the breakage of the frangible disk permits the stored gas to flow out of the pressure vessel in a direction generally about the propellant. The invention additionally includes a diffuser which supports the inflator and provides a flow passage to the air cushion. The diffuser also supports the air cushion. The diffuser envelopes the inflator in a manner to create relatively large volume regions downstream of any gas outlet in the pressure vessel. This design reduces gas turbulence and reduces the amount of heat transfer between the heated inflation gas and the diffuser.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.